Iran's supreme leader delivered a salty rebuke to the U.S. Friday as Iranians lined up to vote in a presidential election that has suddenly become a showdown across the Islamic Republic's political divide: hard-liners looking to cement their control and re-energized reformists backing the lone moderate.

Ayatollah Ali Khamenei responded to U.S. questions over the openness of the balloting, telling Washington "the hell with you" after voting in a race widely criticized in the West as pre-rigged in favor of Tehran's ruling system.

Long lines snaked outside some voting stations in Tehran and elsewhere. Iran's interior ministry extended the voting time by three hours. The enthusiasm suggested an election once viewed as a pre-engineered victory for Iran's ruling establishment has become a chance for reform-minded voters to re-exert their voices after years of withering crackdowns.